The oil pan for the vehicle is generally made of metal because when the oil pan strikes against an obstruction on a road such as a curb then breaks, the oil leaks to the outside.
Meanwhile, weight reduction of the vehicle and use of resin for parts have been progressing in recent years, and there has been a demand that the resin should be used for the oil pan too.
For instance, Patent Document 1 discloses a resin-made oil pan having an impact absorption structure.
This impact absorption structure of the Patent Document 1 is formed from a plurality of impact absorption inner ribs that are formed on and protrude from a lower surface of a bottom wall of the oil pan, a protector cover that covers a lower side of the bottom wall of the oil pan and a plurality of impact absorption outer ribs that are formed on and protrude from this protector cover. The impact absorption structure absorbs the impact of stone chipping etc., which hit the oil pan, by deformation etc. of the impact absorption inner ribs, the impact absorption outer ribs and the protector cover.